7. Both Fell For Someone Of A Different Species
When Thor came to Earth, he quickly fell for the woman who first encountered him (by running him over, nonetheless) - Jane Foster. Foster is an astrophysicist who was out researching with Erik Selvig and Darcy Lewis when she ran in to Thor (literally) and thus embarked on an adventure with him as he seeked out Mjolnir and a way back to Asgard. It was something of a whirlwind romance which developed a little bit more in Thor: The Dark World, despite the fact that Thor, as an Asgardian, would go on to live for thousands of years while Foster would live the life of a normal human. Similarly, Buffy fell for mysterious stranger Angel in the first season of Buffy and their relationship would be on and off for the remainder of the show. Angel was a centuries old vampire who, having fallen afoul of a gypsy tribe, was cursed with a soul and thus a consciousness. They truly loved each other and had many experiences together - both good and bad - despite Buffy being a teenager when they met and despite Angel being so much older (and, of course, despite the fact that he was effectively immortal and she would go on to live a standard human life). Buffy also, to a lesser extent, fell for Spike - another vampire.